1. Field of the Invention
This invention is related to the field of graphical information processing, more particularly, to frame timing synchronization.
2. Description of the Related Art
Part of the operation of many computer systems, including portable digital devices such as mobile phones, notebook computers and the like is the use of some type of display device, such as a liquid crystal display (LCD), to display images, video information/streams, and data. Accordingly, these systems typically incorporate functionality for generating images and data, including video information, which are subsequently output to the display device. Such devices typically include video graphics circuitry to process images and video information for subsequent display.
In digital imaging, the smallest item of information in an image is called a “picture element”, more generally referred to as a “pixel”. For convenience, pixels are generally arranged in a regular two-dimensional grid. By using this arrangement, many common operations can be implemented by uniformly applying the same operation to each pixel independently. Since each pixel is an elemental part of a digital image, a greater number of pixels can provide a more accurate representation of the digital image. The intensity of each pixel can vary, and in color systems each pixel has typically three or four components such as red, green, blue, and black.
Most images and video information displayed on display devices such as LCD screens are interpreted as a succession of image frames, or frames for short. While generally a frame is one of the many still images that make up a complete moving picture or video stream, a frame can also be interpreted more broadly as simply a still image displayed on a digital (discrete, or progressive scan) display. A frame typically consists of a specified number of pixels according to the resolution of the image/video frame. Information associated with a frame typically consists of color values for every pixel to be displayed on the screen. Color values are commonly stored in 1-bit monochrome, 4-bit palletized, 8-bit palletized, 16-bit high color and 24-bit true color formats. An additional alpha channel is oftentimes used to retain information about pixel transparency. The color values can represent information corresponding to any one of a number of color spaces.
In certain situations, video images, or pixel streams provided to a display panel or display interface might have a different resolution than what the display is capable of supporting. Conversely, the display might have a higher native resolution (number of horizontal pixels per number of vertical pixels) than the video images to be displayed. Oftentimes, in order to properly display various images of differing resolution on the same display, a video scaler is used. Typically, video scalers operate to convert video signals from one size or resolution to another, and can be incorporated into computer monitors, scan conversion devices, televisions, video editing and broadcasting equipment, and other audio/visual devices. In any case, there are many different types of video signals and video displays with different respective resolutions, which oftentimes necessitates some form of resolution adaptation, or video scaling, to properly frame a video signal to the display device. Because of the change in the number of pixels per frame from source to destination during a scaling operation, the flow of the pixel data from the source has to be changed with respect to the destination. The effective data rate change between the input frame and the output frame creates a need to retime the pixel stream, which can cause issues in the downstream logic, especially when providing the pixel stream to a third party display interface.
Other corresponding issues related to the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.